Storing users data in a Multidimensional Array in C#

public static void Main()
    {
      String inputname, inputphoneno, userselection;
 
      String[,] addrbook = new string[20, 2];
 
      int n = 0;
      do
      {
        Console.WriteLine("Please select and option" +
        Environment.NewLine + "1. Add Entry" +
        Environment.NewLine + "2. Delete Entry" +
        Environment.NewLine + "3. Print Book to Screen" +
        Environment.NewLine + "4. Quit");
        userselection = Console.ReadLine();
 
        switch (userselection)
        {
          case "1":
            Console.WriteLine("Name:");
            addrbook[n,0] = Console.ReadLine();
            Console.WriteLine("Phone No.:");
            addrbook[n,1] = Console.ReadLine();
            break;
          case "2":
            // code for entry removal
            break;
          case "3":
            // code for printing the address book
            break;
          case "4":
            break;
        }
        n++;
      } while (userselection != "4");
    }